This invention relates to a safety lock for upstackers and in particular upstackers which are constructed with link members to raise and lower the discharge end of the stacker in a generally vertical plane.
Examples of upstackers which operate in the manner described are disclosed in Martin U.S. Pat. No. 2,901,250 granted Aug. 25, 1959, Automatic Sheet Stacker Apparatus; Martin U.S. Pat. No. 3,321,202 granted May 3, 1965 Automatic Sheet Stackers; and Morgan U.S. Pat. No. 6,042,108 granted Mar. 28, 2000 Zero Feed Interrupt Sheet Stacker.
Upstackers of the type disclosed are designed with safety controls to prevent accidental lowering of the upstacker, but a satisfactory mechanical safety lock has not been provided. Various elongated props or poles similar to safety props found in auto shops for hydraulic automobile lifts have been attached to upstackers. Such props are cumbersome and expensive to build and install. Some props are not strong enough to withstand the tremendous hydraulic forces imposed by the operation of the machine.
The present invention provides a mechanical safety lock, which releasably engages and interlocks with the moving parts of the upstacker mechanism in such a way that the number of parts necessary to lock out the upstacker is minimized.
An object of the present invention is to provide a safety lock which is relatively simple to make, easy to install and works as an integral part of the mechanism.
A further object is to provide a safety lock which is very strong and reliable in attaining a lock-out of the upstacker mechanism.
Still another object is to provide a safety lock which is easily and unobtrusively carried as a part of the machine when it is in the inoperative mode.
A still further object is to provide a safety lock which is easily and quickly engaged by the operator.
A further object is to provide a safety lock which signals the operator and others when it is in the lock-out mode.
Still another object is to provide a procedure which is safe and reliable for removing the safety lock from the lock-out mode.